In general, electronic apparatuses such as wireless mobile phones or digital cameras are increasingly miniaturized, and thus mounting of a board applied to the electronic apparatuses has been miniaturized and high-densified.
As chip parts used in Surface Mount Technology (SMT) fields, 0402 types (0.4 mm×0.2 mm) are emerging, and both-sided mounting of a Ball grid array (BGA) or a chip scale package (CSP) having several hundreds of pins are becoming common. Further, as a solder bonding area (solder ball diameter) is increasingly reduced, and lead-free soldering is performed, there is no equipment for properly inspecting bonding intensity of solder bonding or the like, and thus unreliability for the inspection is increasingly growing. Further, a solder bonding portion of a rear of a package such as a BGA is not viewed with the naked eye, and since there is no pin space due to high-density, and thus the In-Circuit tester cannot be used.
Therefore, there is a need for inspection through transmissive X-ray inspection equipment with respect to the portion which is not directly checked with the naked eye as described above.
However, in response to total inspection being performed in a fabrication line, in the transmissive X-ray inspection equipment in the related art, since a professional inspector has to inspect a transmission image displayed on a screen one by one with the naked eye, variation in the determination speed and accuracy is large according to skill of the inspector and it is difficult to find bonding failure in an early stage. Therefore, it is difficult to satisfy quality guarantee desired in the markets.
To solve such problems, an automatic X-ray inspection (AXI) apparatus which can exclude the naked inspection by the inspector and automatically read out a scanned image has been suggested.
As the AXI apparatus in the related art, an oblique type which can do a computed tomography (CT) scan with respect to a mounting state of the board in a state in which an X-ray vacuum tube or a detector is obliquely disposed by representing a 2D image and a 3D image through the scanned image, so as to accurately read out internal defects (void, crack, or the like) of the board.
However, the AXI apparatus in the related art is not suitable for a SMT inline process due to low speed. This is because an image processing rate and mechanical problems are complexly acted.
In particular, in response to the mechanical problems, for example, as the X-ray vacuum tube and a stage are assembled to be integrally coupled, large load is burdened in response to moving the stage and the X-ray vacuum tube.
Further, if necessary in the inspection, since the stage is integrally assembled with the X-ray vacuum tube which has to move horizontally and vertically, due to a structure which cannot be stably supported such as occurrence of vibration in response to high-speed rotation of the stage, there are problems that rotation accuracy of the stage is considerably degraded, and concentricity of the stage is not maintained. The problems become a significant barrier to scan an object to be inspected, and thus a distorted image is formed and reliable inspection cannot be ensured.